5-HT4 receptor has been officially recognized (Humphrey et al., 1993) and identified in a variety of tissues across many species (for review see Ford & Clarke, 1993). 5-HT4 receptor modulators (e.g., agonists and antagonists) are found to be useful for the treatment of a variety of diseases such as gastroesophageal reflux disease, gastrointestinal disease, gastric motility disorder, non-ulcer dyspepsia, functional dyspepsia, irritable bowel syndrome, constipation, dyspepsia, esophagitis, gastroesophageral disease, nausea, central nervous system diseases, cognitive disorders, dementia, attention deficit hyperactivity disorder, schizophrenia and cardiovascular disorders such as cardiac failure and heart arryhthmia (Corsi. M et al., Pharmacological analysis of 5-hydroxytryptamine effects on electrically stimulated human isolated urinary bladder, Br. J. Pharmacol. 1991, 104(3), 719-725; Waikar. M. V et al., Evidence for an inhibitory 5-HT4 receptor in urinary bladder of rhesus and Cynomolgus monkeys, Br. J. Pharmacol. 1994, 111(1), 213-218; Anthony P. D. W. Ford et al., The 5-HT4 Receptor, Med. Res. Rev. 1993, 13(6), 633-662; Gary W. Gullikson et al., Gastrointestinal motility responses to the S and R enantiomers of zacopride a 5-HT4 agonist and 5-HT3 antagonist, Drug Dev. Res. 1992, 26(4), 405-417; Kaumann. A. J et al., A 5-HT4-like receptor in human right atrium, Naunyn-Schmiedeberg's Arch. Pharmacol. 1991, 344(2), 150-159).
Patent publications US 20060194842, US 20080207690, US 20080255113 and US 20080269211 disclosed some 5-HT4 receptor compounds. While some 5-HT4 receptor ligands have been disclosed, and there still exists a need and scope to discover new drugs with novel chemical structures for treatment of disorders affected by 5-HT4 receptor.